1. Field of the Invention
The present invention relates to an image data processing apparatus which processes an input image data sampled for each pixel.
2. Description of the Prior Art
An image processing apparatus which uses an image processing system called a dither method in which an input image data for each pixel is processed by one element of a threshold matrix (dither matrix) to convert it to one-bit or multi-bit data representing a binary or multi-value dot, has been known. An image processing apparatus which uses an image processing system called a density pattern method in which an input image data for each pixel is processed by an entire threshold matrix to produce a dot pattern representing the input data, has also been known.
In the image processing apparatus which uses the density pattern method, the input 6 to 8-bit pixel data is transmitted to an output device such as a printer and it is converted to a dot pattern in the output device, or the input pixel data is stored in a memory and then it is converted to the dot pattern in the output device.
Accordingly, in such image processing device, the input pixel data must be transmitted or stored as it is in spite of the fact that the number of tone levels in the output device is smaller than that of the input pixel data.